Motor fuel and process of improving same



properties of the fuels.

been to introduce a considerable quantity of.

Patented Dec. 8, 1931 LUDWIG- IRDSENSTEIN AND WALTER HUND, SAN FRANCISCO, CALIFORNIA Moron. rum. AND .BROOESS or rmrnovme sum No Drawing.

This invention relates to the improvement of motor fuels, and pertains more par icularly to the introduction into motor fuels, having an appreciable percentage of unsaturated 5' hydrocarbons therein, of compounds which will im rove thecharacter "of the fuel.

is Enown in the art that ,the presence of unsaturates in automobile motor fuels contributes considerably to the anti-detonating The tendency has unsaturates into gasoline for the purpose of increasing its highest useful compression.

value, with the concomitant elimination of a knocking or detonation.

It is, however, known that the presence of unsaturates in gasoline, particularly unsaturates of the diene type, while adding to the efliciency of the fuel for many purposes, gives rise-to a tendency towards the formation of gum-like substances. v This is probably due to the oxidation and polymerizationof the uiisaturated compounds of the gasoline into compounds of high molecular weight. The tendency of unsaturates to form gums, upon exposure to atmospheric conditions, creates a problem, the solution of which is of great value for the advancement of the art.

A feature of our invention consists in the 3 addition to gasolines of this type, namely,

those containing a high percentage of un- 'saturates, of substances whichwill eliminate ,the tendency towards gum formation. I It is a further feature of ourinvention to incorporate into the gasoline substances which not only inhibitgum formation, but which actually add to the fuel value of the gasoline by contributing thereto additional anti-knockroperties. I

More specifically, our invention deals with the treatment of hydrocarbon oils which have been blended with extracts of unsaturates,

by means of-seleno mercaptans, in amounts suflicient to effect the desired result.

Seleno mercaptans are compounds having the characteristic radical SeH, being related'to thio mercaptans which possess the groupSH. These compounds are prepared 60 accordingto methods described in the litera- Application filed August 27, 19cc. Serial No. 478,806.

ture and are comparatively easy and inexpensive of manufacture.

Upon the addition of the seleno mercaptan to the gasoline, there is a spontaneous reace .tion which is preferably continued until the seleno mercaptan completely reacts, with the elimination of the mercaptan group, as such. The products of reaction are, in all probability, addition products of the unsaturated compounds and the mercaptans. The elimination of the mercaptan may be noted by the disappearance of the characteristic ill smell- 111g seleno mercaptan odor. At the same time,

there is formed in the hydrocarbon solution a new compound, or a series of new com pounds, which possess a ,golden yellow tint, are substantially odorless and are entirelydistinct in their character and structure from the seleno mercaptan added in thefirst instance. e r i 1 I The compound formed upon interaction of the seleno mercaptan and the unsaturates in the gasoline is very stable to light, and communicates the same property of color stability to the gasoline in which it is incorporated. c It further has the capacity to inhibit gum formation, even where the seleno mercaptan has been added to the gasoline in a. proportion molecularly much smaller than the percentage of unsaturates present.

The principle involved in the capacity of the gasoline so treated to resist gum formato be an inhibitor of peroxide formation even when present in very small amounts relative to the unsaturates present in the gasoline.

Fuels to which unsaturates have been addi ed, especially compounds of the diene type, acquire a high maximum useful compression value, but this value diminishes progressively upon exposure to atmospheric conditions. The addition of seleno mercaptans in accord- .ance with the'concept of this invention stabilizes the maximum compression value of the fuel per se. 7 In addition to the inhibiting of gum formation and the stabilization of the initial compression value of the fuel, which are features of considerable value, the gasoline so treated has acquired. an anti-detonating faculty which is in excess over and above that possessed due to the presence of the unsaturated hydrocarbons. It is known pounds, in general, and particularly selenium derivatives of hydrocarbons, have antiknock properties. It is likely that the new compound formed by the addition of the mercaptan, being a hydrocarbon derivative of selenium, produces in the gasoline the additional protection against detonation due to the presence of selenium in the solution.

Whatever the theory; behind the phenomenon may be, the fuels'o treated is highly satisfactory for a commercial non-detonating fuel. By means of our process, it is possible to bring up the compression ratio of a gasoline to a predetermined point by the addition of unsaturated hydrocarbons, and then to elevate the compression value still further by the treatment of the fuel with a seleno mercaptan of any desired form, while prevent 'ing gumming and improving color stability. It will-be seen that a very small amount of the seleno derivative need be present in order to obtain the desired maximum useful compression in the fuel.

- It was discovered also that the addition of the seleno mercaptan to the fuel, during treatment'of the same, imparted to the gasoline a characteristic golden yellow tint, which was not present in the seleno mercaptan added to the hydrocarbon mixture. This color effect may be due to the formation of complex selenides. The color efiect created may be utilizedcommercially in distinguishing gasolines which have been treated by means of mercaptans of selenium for the purpose of improving the fuel. This factor eliminates the necessity of adding a coloring agent to a commercial motor fuel, a procedure" which has been adapted quite generally by the art to distinguish the various kinds of gasolines.

In order to introduce a coloring agent into a gasoline, it is necessary that the dye or other coloring matter which is introduced be oil soluble. The number of such dyes, suitable for such use, is limited, and the preparation of the dyes involves a rather expensive process of manufacture. In-view of the fact'that in-our process the coloring matter is formed to the art that selenium com in situ during the treatment of the oil, the expense involved in coloring the gasoline be-- comes negligible Phenyl seleno mercaptan is suitable agent for treating gasolines according to the manner of our invention. However, ethyl and other seleno mercaptans, aliphatic and aromatic, are likewise suitable.

The following 1s an embodiment of one adaptation of the process of our invention A doctor sweet cracked gasoline whose .original benzol equivalent was 17% was that used in the example above given, containing 62.2 mg. of gum per 100 c. c. was exposed to ultra-violet light for 24 hours. The gum content rose to 102.9 mg. per 100 c. c. The gasoline treated in accordance with the example referred to was found to contain 33.5 mg. of gum per 100 c. 0.; and upon ex- .posure to ultra-violet light for a like period of 24'hours, the gum content was found to be 33.7, showing no appreciable increase in gum content, thus indicating the complete effectiveness of the seleno mercaptan to check the tendency toward gum formation.

Many modifications of our process are possible. The number of seleno mercaptans which may be made is practically unlimited. Any compoundwhich contains the characteristic seleno mercaptan group" is suitable for the purposes of the invention. The various mercaptans used may vary in their effect within divergent limits, but this effect will vary in the most part due to the molecular weight of the various substituent radicals which are attached to the seleno mercaptan nucleus. We contemplate any modifications of our process as are within the purview of our invention.

Mercaptans of tellurium, corresponding to those of selenium, will operate in the same way as the selenium mercaptans in our process. Tellurium and selenium are elements which are very closely related in their chemical properties. Their use, in the form of mercaptans, in the treatment of unsaturated gasolines results in a similar effect in the treated gasolines.

We claim 1. A process for improvingthe character of gasolines containing unsaturated hydrocarbons, which comprises adding to the gasolines a predetermined amount 'ofa seleno mercaptan. I

2. A process for improving the quality .of gasolmes containing unsaturated hydro;

carbons, which comprisesadding to the gaso' lines a. predetermined amount of selenomercaptan, and allowing the mercaptan to react completely, with the elimination of the mercaptan as such.

3. A process for improving the quality of gasolines containing unsaturated hydrocar-" bons, which comprises adding to the gasolines a relatively small amount of seleno mercaptan in proportion to the quantity of unsaturates present. I

4. A process for iniproving'th quality of gasolinescontainin unsaturated hydrocarbons, which compnses adding to the gasolines a relatively small amount of seleno mercaptan in proportion tdthe quantity of unsaturates present, and allowing the mercap- -appears. I

' 6. Aprece'ss for treating asolines containing unsaturated hydrocar ons to prevent gum formation and to improve the compression value of the gasoline, which comprises adding to the gasoline an amount of ethyl seleno mercaptan sufiicient toeliminate the. tendency towards gum formation.

7. Aprocess for treating asolines contain; ing unsaturated hydrocar ons to prevent gum formation and to improve the compression value of the gasoline, which comprises adding to the gasoline an,amount of ethyl seleno mercaptan suflicientto eliminate the tendency towards gum formation, and suflie cient also to elevate the compression value of the gasoline to a predetermined maximum hydrocarbons, which has been. treated with a seleno-mercaptan.

hydrocarbons, into which a'seleno ,mercaptan has been introduced.

12. A motor fuel containing unsaturated hydrocarbons, into which a seleno mercaptan has been introduced, and allowed to react completely, with the elimination of the seleno mercaptan as such.

13. A motor fuel containing unsaturated mercaptan has been introduced and allowed to react. completely, with the elimination of the phenyl seleno mercaptan as such.

14. A gasoline containing unsaturated hydrocarbons, and having. a color intensity of prede'tlermined value which has been imparted to it seleno rhercaptan.

K 15. A gasoline-containing unsaturated hydrocarbons, and having a color intensity of predetermined value which has been imparted to it by the addition'and interaction of an ethyl seleno mercaptan.

, In testimony whereof, we afiix our signatures. s

LUDWIG R OSENSTEIN.

WALTER HUND.

11. A .motor fuel containing unsaturated hydrocarbons, ,into which a phenyl seleno.

the addition and interaction of a I which is in excess of that possessed by the gasoline prior to treatment. j

8. A. process for coloringhydroc'arbon fuels, whichcomprises incorporating in the fuels unsaturated hydrocarbons, and subsequently treating the fuels with a seleno mer- 9. A process for coloring motor fuels,

which comprises adding to a hydrocarbon fuel a predetermined amount of unsatiirated 1 hydrocarbon, and subsequently reacting the mixture so formed with an amount of ethyl seleno mercaptan suflicient to give a coloring effect of a predetermined value. v v

10. A motor fuel containing unsaturated 

